Although thermal precleaning has long been a standard procedure in the oil and gas industry as a method of surface preparation for the application of high-bake coatings to the interior surfaces of oilfield tubular goods, it is now commonly used in the process industry as well. The surfaces of tanks, rail tank cars, tubular goods, and process equipment that have been exposed to a corrosive environment are
usually pitted and scaled and contain chemical contaminants both on the surface and within the grain boundaries of the substrate. Failure to remove deleterious amounts of these contaminants ultimately results in blistering and premature failure of the coating. Years of industry experience have shown that abrasive blasting alone will not adequately remove all contaminants, especially in the bottom of pits.
Thermal precleaning is not used exclusively; rather, it is a surface preparation method that, when used in conjunction with other cleaning methods, can achieve the degree of cleanliness required for a successful coating application. Thermal precleaning is typically used in conjunction with abrasive blasting, high-pressure water cleaning, steaming, chemical treatment (e.g., phosphoric acid), or several repetitive applications of thermal precleaning and abrasive blasting in order to facilitate the removal of deleterious levels of salts and carbonaceous materials produced as a result of thermal precleaning.
Within industry there is sufficient experience with thermal precleaning, particularly by coating application shops, to warrant the issuance of this state-of-the-art report by means of which industry can refer to a consensus document for thermal precleaning in coating specifications.
This state-of-the-art report was prepared by NACE/SSPC Task Group B on Surface Preparation by Thermal Cleaning, which is a component of NACE Unit Committee T-6G on Surface Preparation for Protective Coatings and the SSPC Surface Preparation Committee. This report is issued by NACE International under the auspices of Group Committee T-6 on Protective Coatings and Linings and by
SSPC: The Society for Protective Coatings.
